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Standards of Measurement

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Standards of Measurement

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Standards of Measurement

PS-1.3 Use scientific instruments to record measurement data in appropriate metric units that reflect the precision and accuracy of each particular instrument

PS-1.5 Organize and interpret data from a controlled scientific investigation by using mathematics (including formulas and dimensional analysis), graphs, models, and/or technology

- Standard– an exact quantity that people agree to use for comparison to represent a measurement or some other quality
- Le Systeme Internationale d’Unites, SI System, is the system used by scientists and the rest of the world to make measurements
- Each type of measurement has a base unit
- Each base unit has a standard
- Prefixes used with base units that are based on multiples of ten

Length

A. 1 meter or 105 centimeters

B. 4 kilometers or 4400 meters

C. 12 centimeters or 102 millimeters

D. 1200 millimeters or 1 meter

km

Metric Units

m

cm

mm

Length: The distance from point to point.

The basic unit of length in the SI system is the meter and is represented by a lowercase m.

Standard: The distance traveled by light in absolute vacuum in 1⁄299,792,458 of a second.

Measured using a metric ruler or a meter stick.

Metric Units

1 Kilometer (km) = 1000 meters

1 Meter = 100 Centimeters (cm)

1 Meter = 1000 Millimeters (mm)

Which is larger?

1 mile

1.6 kilometers

1 yard = 0.9444 meters

1 inch = 2.54 centimeters

English vs. Metric Units

Which is longer?

A. 1 mile or 1 kilometer

B. 1 yard or 1 meter

C. 1 inch or 1 centimeter

Left Image: http://webapps.lsa.umich.edu/physics/demolab/controls/imagedemosm.aspx?picid=1167Right Image: http://share.lancealan.com/N800%20ruler.jpg

The large lines are the cm

The small lines in between are the millimeters

- Notice there are 10 mm in 1 cm

- 1) Line up one edge of what you are measuring, with the zero mark on the ruler
- Read all the known digits in the measurement, then estimate ONE place value past the known digits…
- ‘Tell what you know… then estimate one number further.’

1 centimeter = 10 millimeters

What is the length of the line in centimeters? _______cm

What is the length of the line in millimeters? _______mm

Measuring Length

How many millimeters are in 1 centimeter?

2.80

28.0

Ruler: http://www.k12math.com/math-concepts/measurement/ruler-cm.jpg

A

43.5 mm4.35 cm

B

60.6 mm 6.06 cm

C

8.5 mm 0.85 cm

D

30.0 mm 3.00 cm

Volume

kL

Metric Units

cL

mL

L

Volume is the amount of space an object takes up.

The base unit of volume in the metric system is the liter (L or l) for liquids and cubic centimeter (cm3) for solid objects.

Standard: 1 liter is equal to one cubicdecimeter

Measured using a Graduated Cylinder

Metric Units

1 liter (L) = 1000 milliliters (mL)

1 milliliter (mL) = 1 cm3 (or cc) = 1 gram*

Which is larger?

A. 1 liter or 1500 milliliters

B. 200 milliliters or 1.2 liters

C. 12 cm3 or 1.2 milliliters*

* When referring to waterLiter Image: http://www.dmturner.org/Teacher/Pictures/liter.gif

1 fl oz = 29.573 ml

1 12-oz can of soda would equal approximately 355 ml.

1 quart = 0.946 liters

1 gallon = 3.79 liters

It would take approximately 3 ¾ 1-liter bottles to equal a gallon.

English vs. Metric Units

Which is larger?

A. 1 liter or 1 gallon

B. 1 liter or 1 quart

C. 1 milliliter or 1 fluid ounce

What causes the meniscus?

A concave meniscus occurs when the molecules of the liquid attract those of the container. The glass attracts the water on the sides.

Measuring Volume

We will be using graduated cylinders to find the volume of liquids and other objects.

Read the measurement based on the bottom of the meniscus or curve. When using a real cylinder, make sure you are eye-level with the level of the water.

What is the volume of water in the cylinder? _____mL

43.0

Top Image: http://www.tea.state.tx.us/student.assessment/resources/online/2006/grade8/science/images/20graphicaa.gifBottom Image: http://morrisonlabs.com/meniscus.htm

Measuring Liquid Volume

What is the volume of water in each cylinder?

37.0 mL

52.0 mL

23.0 mL

Images created at http://www.standards.dfes.gov.uk/primaryframework/downloads/SWF/measuring_cylinder.swf

A

B

C

Pay attention to the scales for each cylinder.

9 cm

8 cm

10 cm

We can measure the volume of irregular object using: water displacement.

Amount of H2O with object = ______About of H2O without object = ______Difference = Volume = ______ = ______

http://resources.edb.gov.hk/~s1sci/R_S1Science/sp/en/syllabus/unit14/new/testingmain1.htm

Measuring Solid Volume

We can measure the volume of a regular object using the formula: length x width x height.

_____ X _____ X _____ = _____

10cm

8cm

9cm

720 cm3

260 mL

200 mL

60 mL

60 cm3

Mass

Kilogram Prototype

A. 1 kilogram or 1500 grams

B. 1200 milligrams or 1 gram

C. 12 milligrams or 12 kilograms

D. 4 kilograms or 4500 grams

kg

Metric Units

cg

mg

g

Mass refers to the amount of matter in an object.

The base unit of mass in the metric system in the kilogram and is represented by kg.

Standard: 1 kilogram is equal to the mass of the International Prototype Kilogram (IPK), a platinum-iridium cylinder kept by the BIPM at Sèvres, France.

Mass is measured using a triple beam balance.

Metric Units

1 Kilogram (km) = 1000 Grams (g)

1 Gram (g) = 1000 Milligrams (mg)

Which is larger?

Kilogram Prototype Image - http://en.wikipedia.org/wiki/Kilogram

1 pound = 453.6 grams

1 ounce of gold = 28,349.5 milligrams

100 kilogram = 220 pounds

English vs. Metric Units

Which is larger?

1. 1 Pound or 100 Grams

2. 1 Kilogram or 1 Pound

3. 1 Ounce or 1000 Milligrams

Once you have calibrated the balance and placed the ‘tares in their notches’, you add up the amounts on each beam to find the total mass.

What would be the mass of the object measured in the picture?

_______ + ______ + _______ = ________ g

Measuring Mass

We will be using triple-beam balances to find the mass of various objects.

To begin, you must ‘calibrate’ the balance. The ‘weights’ are all aligned to the far left… near the tray… then you turn the knob under the tray until you get the lines on the right-side of the scale to match up.

373.35

70

3.35

300

Top Image: http://www.southwestscales.com/Ohaus_Triple_Beam_750-SO.jpgBottom Image: http://www.regentsprep.org/Regents/biology/units/laboratory/graphics/triplebeambalance.jpg

1st – Place the object on the balance, in the center of the tray.

2nd – Slide the large weight to the right until the arm drops below the line. Move the tare back one notch. Make sure it ‘locks’ into place.

3rd – Repeat this process with the top weight. When the arm moves below the line, back it up one notch.

4th – Slide the small slider tare on the front beam until the lines match up.

Measuring Mass – Triple-Beam Balance

5th – Add the amounts on each beam to find the total mass to the nearest tenth of a gram, then estimate one number further.

0

100

200

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10

20

30

40

50

60

70

80

90

100

0

1

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3

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10

137.45g

0

100

200

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20

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70

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90

100

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10

203.25g

0

100

200

0

10

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100

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10

43.05g

Time and Temperature

Time - Interval between two events

The base unit of time is thesecond (s).

Standard: The frequency of the cesium-133 atom as the ‘reference clock’

Time is measured with a clock/ stop watch.

Temperature–“how hot or cold something is”

The base unit in the ‘old’ Metric system is degrees Celsius (˚C)

The base unit in the modern SI system is the Kelvin (K)

Standard: Based on freezing and boiling points of pure water at standard temperature and pressure… (0˚C and 100˚C at 1atm)

Measured with a thermometer

°C + 273 = K

Thirty is HOT, Twenty is NICE,

Ten is CHILLY, and

Zero is ICE!!

Accuracy and Precision

- Accuracy – How close value is to accepted value (control)
- Precision – how close repeated measurements are to one another
- Determined by the measuring device being used
- The smaller the Graduations… the more Precise the measurement! And the more likely it is to be repeated

Kilo (k) = 1000x

hecta (h) = 100x

deka (dk) = 10x

deci (d) = .1x or 1/10

centi (c) = .01x or 1/100

milli (m) = .001x or 1/1000

PS- 1.2 Use appropriate laboratory apparatuses, technology, and techniques safely and accurately when conducting a scientific investigation.

PS- 1.9 Use appropriate safety procedures when conducting investigations.

1 milliliter (ml) = 1 cubic centimeter (cm3) = 1 gram (g)

For Everything Else

1 milliliter (ml) = 1 cubic centimeter (cm3)

Solids - cm3

Liquids – ml

Gases – either one

DON’T FORGET YOUR UNITS!!

Measurement

Lab